strapi build only on master or main

strapi/build.yml

@@ -8,4 +8,7 @@ build:
   script:
     - docker login -u $ACR_USERNAME -p $ACR_PASSWORD $ACR_URL
     - docker image build --build-arg REG=https://artifact.tecnalia.com/artifactory/api/npm/digicon-npm-dev/ --build-arg NPM_TKN=$NPM_TOKEN --build-arg US=$ACR_USERNAME  --build-arg CI_TOKEN=$ACR_PASSWORD --build-arg DATABASE_HOST=$DATABASE_HOST --build-arg DATABASE_NAME=$DATABASE_NAME  --build-arg DATABASE_USERNAME=$DATABASE_USERNAME --build-arg DATABASE_PASSWORD=$DATABASE_PASSWORD --build-arg PRODUCTION_HOST=$PRODUCTION_HOST -t $CONTAINER_IMAGE ./
-    - docker push $CONTAINER_IMAGE
\ No newline at end of file
+    - docker push $CONTAINER_IMAGE
+  only:
+    - master  
+    - main
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